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Nuclear gene location. A nuclear gene is a gene that has its DNA nucleotide sequence physically situated within the cell nucleus of a eukaryotic organism. This term is employed to differentiate nuclear genes, which are located in the cell nucleus, from genes that are found in mitochondria or chloroplasts. The vast majority of genes in ...
Nuclear DNA and mitochondrial DNA differ in many ways, starting with location and structure. Nuclear DNA is located within the nucleus of eukaryote cells and usually has two copies per cell while mitochondrial DNA is located in the mitochondria and contains 100–1,000 copies per cell.
The nuclear envelope consists of two membranes, an inner and an outer nuclear membrane, perforated by nuclear pores. [ 10 ] : 649 Together, these membranes serve to separate the cell's genetic material from the rest of the cell contents, and allow the nucleus to maintain an environment distinct from the rest of the cell.
The human genome is a complete set of nucleic acid sequences for humans, encoded as the DNA within each of the 24 distinct chromosomes in the cell nucleus. A small DNA molecule is found within individual mitochondria. These are usually treated separately as the nuclear genome and the mitochondrial genome. [1]
All living cells contain both DNA and RNA (except some cells such as mature red blood cells), while viruses contain either DNA or RNA, but usually not both. [15] The basic component of biological nucleic acids is the nucleotide , each of which contains a pentose sugar ( ribose or deoxyribose ), a phosphate group, and a nucleobase . [ 16 ]
However, in order for the cell to function, proteins must be able to access the sequence information contained within the DNA, in spite of its tightly-packed nature. Hence, the cell has a number of mechanisms in place to control how DNA is organized. [4] Moreover, nuclear organization can play a role in establishing cell identity.
Saccharomyces cerevisiae was the first eukaryotic organism to have its complete genome sequence determined.. This list of "sequenced" eukaryotic genomes contains all the eukaryotes known to have publicly available complete nuclear and organelle genome sequences that have been sequenced, assembled, annotated and published; draft genomes are not included, nor are organelle-only sequences.
The amount of mitochondria per cell also varies by cell type, with some examples being: Erythrocytes: 0 mitochondria per cell. [1] Lymphocytes: 3 mitochondria per cell. [7] Egg cell: Mature metaphase II egg cells can contain 100,000 mitochondria, and 50,000–1,500,000 copies of the mitochondrial genome (corresponding to up to 90% of the egg ...